Carborundum is obtained when silica is heated at high temperature with

Which of the following,on reaction with water,will have a $pH$ less than $7$?

Identify $B$ in the following reaction:
$H_4SiO_4$ $\xrightarrow[{-H_2O}]{1000^{\circ}C} A$ $\xrightarrow[\Delta]{Carbon} B + CO$

Identify the incorrect statement about silica $(SiO_2)$.

$A$ tetravalent element forms monoxide and dioxide with oxygen. When air is passed over the heated element $(1273 \ K)$,producer gas is obtained. The monoxide of the element is a powerful reducing agent and reduces ferric oxide to iron. Identify the element and write the formulas of its monoxide and dioxide. Write chemical equations for the formation of producer gas and the reduction of ferric oxide with the monoxide.

Graphite is soft while diamond is hard because